The purpose of the present pilot study is to evaluate, through gait analysis and rating scales, the functional outcome during the execution of motor tasks with high functional demand such as walking on an unstable surface, stair ascent and descent, maximal knee flexion under load (lunge) on a sample of 20 subjects candidates to cemented total knee arthroplasty with MP design at the Orthopedic and Traumatology Clinic 2nd of the Rizzoli Orthopedic Institute. The parameters obtained will be compared with the parameters of healthy subjects comparable by age and Body Max Index (BMI) already acquired at the Movement Analysis Laboratory of the Rizzoli Orthopedic Institute, where the study will be conducted.

On the day of admission to the ward (generally the day before the scheduled surgery), the enrolled patients will undergo the evaluation scales and gait analysis at the Institute's Movement Analysis Laboratory.

The patients will be operated by the team of the Traumatological Orthopedic Clinic 2nd through the implantation of a cemented total knee prosthesis MP (Evolution medial-pivot knee system, MicroPort Orthopedics). Anterior knee access with medial para-patellar capsulotomy and standard instruments will be used according to current standards of good clinical practice.

In the post-operative period, patients will carry out post-surgical rehabilitation following normal clinical practice.

The patients will be re-evaluated at a 6-month follow-up through gait analysis and evaluation scales on the occasion of the control visit that takes place, according to the normal clinical practice at the Institute.

Total knee prosthesis (PTG) is a widespread surgical procedure that aims to treat severe knee osteoarthritis. This type of intervention has proved successful in reducing chronic pain caused by osteoarthritis and in improving the motor performance of the operated subject as well as the quality of life even if the functional outcome after this procedure is still limited, especially in the execution of more complex and demanding motor tasks (e.g. climbing and descending stairs, walking on unstable surfaces, maximum knee flexion under load) due to the difficulty in finding a prosthetic design that mimics the natural joint biomechanics of a non-arthrosic knee.

Medial Pivot (MP) knee prostheses have been designed to meet these requirements by replicating the morphology of the healthy knee, characterized by a medial compartment with a stable conformation and a movable lateral compartment that moves by rotating around the pivot point. Despite the theoretical premises of this prosthetic model, in literature very few studies have investigated how the MP design translates into an improvement of the functional outcome of the subject operated during the journey, while no study has ever been conducted to evaluate the functional outcome during the execution of more demanding motor tasks although the subjects who undergo knee arthroplasty are always younger and more and more active, with increasingly higher functional needs. To date, gait analysis, a non-invasive functional assessment method that provides objective and quantitative data about spatio-temporal parameters, kinematics, kinetics and muscle activation, represents the Gold Standard for the assessment of functional outcome both in healthy patients and in patients subjected to prosthetic surgery.

The purpose of the present pilot study is to evaluate, through gait analysis and rating scales, the functional outcome during the execution of motor tasks with high functional demand such as walking on an unstable surface, stair ascent and descent, maximal knee flexion under load (lunge) on a sample of 20 subjects candidates to cemented total knee arthroplasty with MP design at the Orthopedic and Traumatology Clinic 2nd of the Rizzoli Orthopedic Institute. The parameters obtained will be compared with the parameters of healthy subjects comparable by age and Body Max Index (BMI) already acquired at the Movement Analysis Laboratory of the Rizzoli Orthopedic Institute, where the study will be conducted.

The pilot study is necessary to carry out a preliminary assessment of the functional outcome and joint biomechanics of the knee prosthesis with the gait analysis method never performed in other studies during the execution of demanding motor tasks, with high functional demand. The collection of information and data obtained will allow the appropriate calculation of the sample useful for a subsequent study.

During the pre-hospitalization visit, participation in the study will be proposed to those who meet the inclusion criteria. If the subject accepts, he will be recruited and will have to sign the informed consent to the study.

On the day of admission to the ward (generally the day before the scheduled surgery), the enrolled patients will undergo the evaluation scales and gait analysis at the Institute's Movement Analysis Laboratory.

The patients will be operated by the team of the Traumatological Orthopedic Clinic 2nd through the implantation of a cemented total knee prosthesis MP (Evolution medial-pivot knee system, MicroPort Orthopedics). Anterior knee access with medial para-patellar capsulotomy and standard instruments will be used according to current standards of good clinical practice.

In the post-operative period, patients will carry out post-surgical rehabilitation following normal clinical practice.

The patients will be re-evaluated at a 6-month follow-up through gait analysis and evaluation scales on the occasion of the control visit that takes place, according to the normal clinical practice at the Institute.

Inclusion Criteria:

• Age: 50-75 years of both gender
• Patients with three-compartment knee arthrosis (primary or secondary post-traumatic)
• Patients with femoral or tibial osteonecrosis
• Patients with posterior cruciate ligament and healthy collateral ligaments at the level of the affected knee
• Deformity in varus or valgus inferior to 10 °
• Person able to provide informed consent and who agrees to sign the Informed Consent Form approved by the Ethics Committee (EC).
• Subject compliant with post-operative rehabilitation to be performed according to normal clinical practice

Exclusion Criteria:

• Patients with severe morphostructural alterations or other pathologies affecting the knee and lower limb
• Patients with serious systemic vascular and neurological pathologies
• Obese or body mass index BMI> 30 kg / m2
• Patients with posterior cruciate ligament and / or collateral ligaments injury in the affected knee
• Knee arthroplasty in the contralateral
• Patient not compliant with post-operative rehabilitation